This invention relates to nuclear fuel storage apparatus for storage of fuel within water-filled pools, and in particular to such a storage rack for use in seismic areas.
Fuel assemblies for nuclear reactors are conventionally stored both before and after use in water-filled pools. They are supported at a lower elevation and restrained within a grid work at an upper elevation.
In the event of an earthquake the horizontal translation of the fuel assemblies imposes significant forces on the grid structure which is in turn transmitted to the pool wall. These forces are passed to the wall by compression with no contribution of a tension force from the opposite wall. The structure cannot be rigidly connected on all four sides since provisions must be made for expansion of the members due to the heat generated within the pool.
The imposition of the full acceleration force of the entire storage rack on a single wall requires that each of the walls be structurally designed for these large forces. Furthermore, when a storage pool has been designed for moderate fuel storage and the fuel storage capabilities of the rack increase, the preexisting design strength of the wall may be insufficient to take new, increased loadings.